People commonly store files, especially photos and documents, on network-based shared storage services. A common use of such storage services is for a user to share files with other users.
Sharing of files generally involves a user defining a folder for the files to be shared. Then the user authorizes one or more other users to access the folder. Files generally are either copied or moved into the folder. If a file is shared in different ways with different users, then the file is generally copied to multiple folders. For example, a user may share a photo and a document with a first user, but then the photo and a different photo, but not the document, with a second user. In such a case, the photo and document are placed in a first folder to which the first user is granted access. The photo and the other photo are placed in a second folder to which the second user is granted access. Alternatively the photo that is shared with both users can be placed in a separate folder to which both the first and second user are granted access.
Such tracking of folders, and copying and moving of files, makes for a difficult and cumbersome user experience. Also, sharing files in this way typically results in multiple different copies of files, thus unnecessarily consuming more storage.